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Backwards-incompatible changes:
- Moved all the partials to live the betterforms directory
- Dropped support for Django 1.3
New Features and Bugfixes:
- Support Python 3
- Support Django 1.6
- Add MultiForm and MultiModelForm
- Make NonBraindamagedErrorMixin use error_class
- Use NON_FIELD_ERRORS constant instead of hardcoded value
- Add csrf_exempt argument for form_as_fieldsets
- Add legend attribute to Fieldset